Peter Landesman — the director of “Mark Felt: The Man Who Brought Down the White House,” about the identity of Deep Throat — says Felt was ashamed of the nickname given to him during the Watergate investigation.

The pseudonym for Bob Woodward and Carl Bernstein’s secret Watergate source “was a porn reference and was actually one of the reasons Mark felt so ashamed,” Landesman told us. “He was a real Christian, and that actually was a big deal for him.”

Felt had been the No. 2 official at the FBI in the 1970s and finally came out as the secret source in 2005 at age 91.